Ulrich Bremer, the spokesman for the Cologne prosecutor's office, said that at least one of the men in custody is accused of groping and robbery, and at least two are accused of robbery alone. It's not clear what the other five are accused of doing.

Nor were all eight men's immigration status officially known.

But Bremer said 21 suspects originally identified by authorities consisted of some illegally in Germany and some who sought asylum. The latter group included those who've been granted asylum and others waiting for their applications to be granted, the spokesman explained.

Six woman in Zurich, Switzerland, for instance, told authorities they were "robbed from one side, (while) being groped ... on the other side" by groups of men, police there said. Police in Helsinki, Finland, investigated two possible crimes involving "a gathering of asylum-seekers." And at least 50 incidents were reported in the northern German city of Hamburg.

Yet what happened in Cologne got the most attention internationally, with police reporting upwards of 581 criminal complaints, more than half of which included alleged sexual offenses.

The idea of mass attacks on women walking through Cologne's city center was horrific enough. But what made it more jarring for some was the allegation that those responsible had been welcomed into Germany: Interior Ministry spokesman Tobias Plate said this month that the suspects included citizens of Algeria, Morocco, Iran and Syria, among other nations.